Something

	if	(strcmp(cmd, "/v", true)==0)
		{
 	    tmp = strtok(cmdtext, idx);
		if	(!strlen(tmp))
			{
			// == means DEFAULTS so you are not force to enter those values
			SendClientMessage(playerid, 0xFFFF00AA, "USE: /v [modelid] [delay==-1] [color1==random] [color2==random]");
			return 1;
			}
        new mid = strval(tmp);
       	if 	((mid<400)||(mid>611))
			{
			SendClientMessage(playerid, 0xAA3333AA, "WARNING! WRONG MODEL ID");
			return 1;
			}
        new delay;
		if	(!strlen(tmp))
			{
			delay = -1;
			}
		else{
		    delay = strval(tmp);
		    }
        new color1;
		if	(!strlen(tmp))
			{
			color1 = random(50);
			}
		else{
		    color1 = strval(tmp);
		    }
  		new color2;
		if	(!strlen(tmp))
			{
			color2 = random(50);
			}
		else{
		    color2 = strval(tmp);
		    }
		new Float:pX, Float:pY, Float:pZ, Float:pAng;
		GetPlayerPos(playerid,pX,pY,pZ);
		GetPlayerFacingAngle(playerid,pAng);
        new CurrentVehicle = CreateVehicle(mid,pX+3.0*floatsin(-pAng,degrees),pY+3.0*floatcos(-pAng,degrees),pZ+0.5,pAng+90.0, color1, color2, delay);		format(tmp, sizeof(tmp), "New vehicle id is: %d and its model is: %d",CurrentVehicle,mid);
		SendClientMessage(playerid, COLOR_BLUE, tmp);
		return 1;
		}